Bacterial endotoxins are produced by Gram negative bacteria and are considered by most investigators to be a very important factor in the development of septecemia. Several methods for determination of endotoxin have been described based on the observation by Levin and Bang (1956)that endotoxins specifically activate the clotting system of Limulus Potyphemus. In the beginning a test, in which Limulus Amebocyte Lysate (LAL)in contact with endotoxins containing sources, produce a specific gelation, had been developed. More recently chromogenic and fluorogenic methods based on the above observation have been developed and can rapidly detect small amounts of endotoxins (H. C. Hemker: Handbook of Synthetic Substrates, 1983, Martinus Nijhoff Publisher, Boston).